Modeling and experimental investigation on water-driven steam injector for waste heat recovery

This paper discusses a proposed model of the water-driven steam injector that can be used to recover waste heat in many industries. A mathematical model was developed for evaluating the injector recovery performance in this study; the results indicated that a higher inlet steam pressure, lower inlet-driven water temperature or lower inlet-driven water pressure improved the entrainment ratio, whereas the back pressure of the discharge water had little effect on the injector performance. Moreover, a one-dimensional two-fluid analytical model of two-phase flow was presented with a set of closure equations for estimating flow parameters of the whole injector. The one-dimensional model involved a single distinct flow regime, inverted annular flow in the mixing nozzle and throat tube of the injector. The condensation heat transfer and interfacial shear stress were found to be two main factors affecting the static pressure profiles along the injector. A series of experiments were conducted to investigate the performance of the injector and the pressure distribution along the injector under different operating conditions. The entrainment ratio and flow parameters along the condensing section of the models were reasonably consistent with the experimental data.